Double Eccentric Valve Sealing via Stopper-Induced Shaft Tilt
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Solution Overview
Problem
In double eccentric valves, the valve element separates from the valve seat during non-energization of the drive source, creating a clearance that can lead to foreign matter entrapment and mal-operation.
Innovation Solution
A double eccentric valve configuration that includes a full-close stopper and a return spring mechanism, where the valve gear contacts the full-close stopper to tilt the rotary shaft and press the valve element against the valve seat, ensuring sealing even when the drive source is not energized, using a cantilever configuration and bearings to maintain a minute clearance and maximize the tilting force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the valve element is allowed to separate from the valve seat during non-energization of the drive source, then the valve element can be returned to the open position by the return spring, but a clearance is created between the valve seat and the valve element that can lead to foreign matter entrapment and mal-operation
Solution Approach 1:
The full-close stopper is positioned to contact the valve gear before the return spring can fully separate the valve element from the valve seat. This preliminary contact prevents the harmful clearance formation by counteracting the return spring's separating force at the critical moment, thereby maintaining sealing reliability while still allowing controlled return operation.
Solution Approach 2:
The full-close stopper acts as an intermediary component between the valve gear and the return spring mechanism. It mediates the interaction by providing a mechanical constraint that limits the separation distance, allowing the return spring to function while preventing excessive clearance that would compromise sealing.
2Reliability
If the valve element is pressed against the valve seat during non-driving of the drive source, then sealing is maintained and foreign matter entrapment is prevented, but the valve element cannot be easily returned to the open position
Solution Approach 1:
The full-close stopper provides preliminary constraint during the return stroke, ensuring the valve element maintains contact with the valve seat until the drive source actively opens it. This prevents sealing loss while the drive source overcomes the holding force to initiate opening motion.
Solution Approach 2:
The return spring is pre-loaded to maintain the valve element in the closed position against the valve seat. This preliminary action ensures sealing is established before any opening operation begins, and the full-close stopper reinforces this by mechanically preventing premature separation.
3Extent of automation
If a return spring is used to rotate the rotary shaft in the valve-closing direction, then the valve element can be automatically returned to the closed position, but the spring force may cause the valve element to separate from the valve seat during non-energization
Solution Approach 1:
The full-close stopper counteracts the automatic return spring action by providing a mechanical constraint that prevents the valve element from separating from the valve seat. The stopper's contact with the valve gear creates a balancing moment that neutralizes the return spring's separating force in the closed position.
Solution Approach 2:
The system changes the operational parameters of the return spring by introducing the full-close stopper constraint. The spring force parameter is effectively modulated - it remains active for automatic return but is counterbalanced by the stopper's mechanical constraint when the valve is closed, creating a conditional behavior that maintains sealing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The valve element is effectively pressed against the valve seat to maintain sealing during non-driving of the drive source, preventing foreign matter entrapment and ensuring reliable operation.
Implementation Method 1
a return spring to apply a spring force of rotating the rotary shaft in a direction to close the valve element to the valve gear
Implementation Method 2
a bearing placed on a side of the proximal end portion of the rotary shaft to rotatably support the rotary shaft with the leading end portion thereof as a free end in cantilever configuration
Implementation Method 3
the part of the valve gear is configured to be contacted to the full-close stopper by the spring force applied to the valve gear during non-driving of the drive source to apply the moment acting on the valve gear to the rotary shaft at a contact point of the valve gear with the full-close stopper as a fulcrum
Implementation Method 4
an axial line of the rotary shaft extends in parallel to a radial direction of the valve element and the valve hole and is placed eccentrically from a center of the valve hole to another radial direction of the valve hole
Data Source
AI summary
A double eccentric valve: a valve seat; a rotary shaft; a valve gear with a rotary shaft base end portion; a motor rotating the shaft via a valve gear; bearings supporting the shaft in a cantilever manner; a return spring giving, to the valve gear, spring force for rotating the shaft in a valve body closing direction; and a full-close stopper to restrict valve gear rotation with the shaft when the valve body is fully closed. When the motor is not driven, the valve gear partially contacts the full-close stopper by spring force, moment acting on the valve gear is caused to act on the rotary shaft with the contact point serving as a fulcrum, the rotary shaft is tilted toward the valve seat with the contact point between the rotary shaft and the bearing serving as a fulcrum, and thus, the valve body is pressed against the valve seat.